Built-up abrasive element



April 10, 1934. STRATFQRD' 1,954,655

BUILT-UP ABRAS IVE ELEMENT Filed 0013.. 15, 1951 INVENTOR.

Herder? 1?,5'2 '4 {ford ATTORNEYS.

ag/MW @aq Patented Apr. 10, 1934 PATENT OFFICE BUILT-UP ABRASIVE ELEMENT Herbert n. Strati'ord, Cleveland, Ohio, assignor m The Stratmore Company, Cleveland, Ohio, a

corporation of Ohio Application October 15, 1931, Serial No. 568,911 4' Claims. (01. 51-195) This invention relates, as indicated, to a built-- up abrasive element having improved properties and operating characteristics. More particularly, the invention relates to an abrasive element hav- 5 ing the abrasive disposed in layers throughout its structure and which may be used in "the form of discs, wheels, pads, or other suitable forms.

Abrasive wheels for grinding surfaces are well known and are usually composed of some hard and strong material. Softer or more friable wheels for certain kinds of work are sometimes desired and compositions having abrasive distributed throughout their mass have been suggested for such use. However, such compositions do not have great strength and wheels prepared therefrom cannot be revolved at very great speeds. A need has been felt for an abrasive wheel or other abrasive element which wouldv have an abrasive structure throughout so that it could be used continuously for long periods of time, and having a strength surpassing that of composition elements. The present invention provides an abrasive device which fulfills the need for an abrading means having the foregoing characteristics.

It is, accordingly, an object of. the' invention to provide an abrasive element having both strength and a prolonged useful life. Another object of the invention is toprovide an abrasive 0 element having the strength of a fibrous material and theabrasive characteristics of a composition. Still another object of the invention is to provide a method of forming such improved abrasive element. A further object of the invention is to provide a method of forming an abrasive element during the process of hydrolyzing cellulose material.

To the accomplishment of' the foregoing and related ends, said invention, then, consists of the 40 means hereinafter fully described and particularly pointed out in the claims. The annexed drawing and the following description set forth in detail one approved method of carrying out the invention,- such disclosed mode, however, constituting but one of the various ways in which the principle of the invention may be used.

In said annexed drawing: Fig. 1 is a section through a block of the new built-up abrasive material; and Fig. 2 is a perspective of a wheel or disc embodying the new abrasive structure. s

' Referring to the drawing, and more particularly to Fig. 1, alternate layers of cellulosic material 3 have disposed between them layers of abrasive 4, the layers being held together by means of an adhesive, such as ordinary glue or waterproof glue or other adhesive substance. The built-up structure may take the form of a wheel, as shown in Fig. 2, in which case the outer-faces 5 of the disc need not carry abrasive 50 although such abrasive is shown.

In making the new abrasive element, thin sheets of cellulose material having a thickness, for example, of .005 to .010 inches are covered with an adhesive and abrasive is then spread on the 5 wet adhesive. A multiplicity of these sheets are then placed in a press or other pressure device and forced together under a pressure of conside erable magnitude. This'pressure is maintained until the glue or other adhesive has set, where- 70, upon the product may be removed and cut to the shape desired, or the individual sheets may have been cut to the desired shape before placing in the'press, in which case the product leaving the press will have the form'in which it is to 7 be used.

While various kinds of fibrous materials may be used for the sheets, it has been found that hydrolyzed cellulose material, such as vulcanized fibre, over-beaten paper stock, and the like, is particularly valuable since it has great inherent strength and a construction formed from aplurality of layers of this material will have the combined strength of the individual sheets plus the strength imparted by the layers of adhesive. Permitting the glue or other adhesive to set under pressure also increases the strength of the built-up construction since the bonding power of glue increases with the pressure under which it is caused to set. In the preferred 907 method of forming the new abrasive element, the pressure maintained is of a magnitude great enough to force individual particles of abrasive into the surface of adjoining sheets of fibre or other material used. As a consequence, the distance between individual abrasive particles in one layer and those in the next will be less than the average thickness of the intervening fibrous sheet.

The'new abrasive element may also be made by taking advantage of the nature of the process for preparing vulcanized fibre or other hydrolyzed cellulose-fibre from paper. In making vulcanized fibre, several sheets of paper may be passed through a bath of zinc chloride until individual 5 fibres of the paper are somewhat gelatinized, whereupon the individual sheets are pressed together and the gelatinous coating cements the fibres into a thicker sheet of fibre. This is then washed to remove the zinc chloride and otherwise no conventionally treated to produce a commercial product. Since the abrasive element described above consists of a plurality of layers of vulcanized fibre, or the like, separated by layers of abrasive, the built-up construction comprised by the present invention may economically be made by interspersing layers of abrasive between layers of paper or other cellulose material and then passing the layers through a zinc chloride bath or other hydrolyzing medium. The gelatinous coating'developed on the individual sheets will then serve in place of an added adhesive to bind the sheets together and enclose the abrasive between them. Pressure may then be applied as above to force the layers closely together and to cause some of the abrasive particles to penetrate the fibre layers. Washing steps and other conventional procedure may then be carried out on the product.

Where the new built-up construction is used as a wheel, the edges of the various layers will be presented to the work and the individual layers of abrasive will be so close together due to the thinness of the separating fibre layers and also to the fact that individual abrasive particles have been mashed into the fibre layers, that a practically continuous abrasive surface will be presented to the work. The strength of the wheel is so great due to the natural strength of 'the fibre layers increased by the layers 01' adhesive which have been allowed to set under pressure, that the wheel can be rotated at any useful speed.

For some classes of work, discs may also be constructed, in accordance with the principles above set forth. Such discs should be constructed from alternate layers of abrasive and fibrous material with the particular class of work in mind for which the disc is intended to be used. In such cases discs may be constructed for certain purposes having the strength and other valuable characteristics resulting from the practice of the present invention.

It will thus be seen from the foregoing that a new abrasive structure has been provided having great strength which will permit it to be used under the most arduous conditions while dispersal of the abrasive medium in layers through the structure permits articles made therefrom to be used for extended periods of time before being used up and discarded.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made in the form or composition, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A method of making an abrasive element which comprises placing abrasive between layers of cellulosic material, passing said layers together through a bath which will hydrolyze the cellulosic material and then forming a composite sheet from said layers of cellulosic material and abrasive.

2. A method of making an abrasive element which comprises placing abrasive between layers 100 of cellulosic material, passing said layers through a bath of zinc chloride, and then pressing said sheets together to form a composite sheet includ-' ing said abrasive.

3. The method of uniting a layer of abrasive material to a layer of cellulosic material consisting of placing said layers in contact and hydrolyzing said cellulosic material.

4. The method of making an abrasive element which comprises the steps of uniting a plurality of alternate layers of cellulosic material and of abrasive material, hydrolyzing said cellulosic material and then pressing said layers together to force some of the abrasiveparticles of each layer to penetrate the adjoining layers of cellulosic material.

' HERBERT 'R. S'I'RA'I'FORD. 

